A disk drive is an information storage device. A disk drive includes one or more disks clamped to a rotating spindle and at least one head for reading information representing data from and/or writing data to the surfaces of each disk. The head is supported by a suspension coupled to an actuator that may be driven by a voice coil motor. Control electronics in the disk drive provide electrical signals to the voice coil motor to move the head to desired positions on the disks to read and write the data in tracks on the disks.
Servo wedges are commonly written onto a disk surface to locate the read/write head on the disk surface during operation. Because tracks are never absolutely perfect circles on a disk, an amount of track mis-registration (TMR) is measured, and used to evaluate a number of operations in a drive such as quality of self-servo writing. Another use for TMR data includes evaluation of a wedge offset reduction field. It is desirable to obtain a measure of TMR that provides the most useful statistical information about the track for a given drive function such as self-servo writing, wedge offset reduction, etc.